Despite the heavy burden of HIV infection among incarcerated people, testing strategies vary widely across US state prison systems. In 19 states, prison systems enforce mandatory HIV testing;the other 31 state prison systems, which incarcerate 70% of all inmates, employ some degree of voluntary testing. Few studies, however, have systematically explored the extent or effectiveness of voluntary HIV testing in state prison systems. Given the lack of knowledge regarding HIV testing in Voluntary'prison systems and the benefits of testing accrued by both infected inmates and communities to which inmates return, we propose to accomplish the following specific aims within the context of a large, southern state prison system: 1) determine system-wide and facility specific HIV testing rates among new prison entrants, 2) explore facility-specific differences associated with HIV testing rates, 3) identify inmate characteristics associated with receipt of an HIV test, and 4) identify inmate characteristics associated with positive serostatus. These aims will be achieved by analyzing a large (N=72,000) database using advanced statistical techniques including hierarchical multivariate modeling and principal components analysis.